class Solution {
public:
    int minDistance(string word1, string word2) {
        
        int m = word1.size(), n = word2.size();

        if(m == 0) return n;
        else if(n==0) return m;

        vector<vector<int>> dp(m+1, vector<int>(n+1, 0));
        
        for(int i = 0; i <= m; i++){
            dp[i][0] = i;
            for(int j = 1; j <= n; j++){
                if(i == 0) dp[i][j] = j;
                else{
                    dp[i][j] = min(dp[i][j-1]+1, dp[i-1][j]+1);
                    if(word1[i-1] != word2[j-1]) dp[i][j] = min(dp[i][j], dp[i-1][j-1]+1);
                    else dp[i][j] = min(dp[i][j], dp[i-1][j-1]);
                }
            }
        }

        return dp.back().back();
    }
};